Cu-Ni-Co-Si based copper alloy sheet material and method for producing the same

Abstract

A Cu—Ni—Co—Si based copper alloy sheet material has second phase particles existing in a matrix, with a number density of ultrafine second phase particles is 1.0×109 number / mm2 or more. A number density of fine second phase particles is not more than 5.0×107 number / mm2. A number density of coarse second phase particles is 1.0×105 number / mm2 or more and not more than 1.0×106 number / mm2. The material has crystal orientation satisfying the following equation (1):I{200} / I0{200}≧3.0  (1)wherein I{200} represents an integrated intensity of an X-ray diffraction peak of the {200} crystal plane on the sheet material sheet surface; and I0{200} represents an integrated intensity of an X-ray diffraction peak of the {200} crystal plane in a pure copper standard powder sample.

Description

TECHNICAL FIELD[0001]The present invention relates to a Cu—Ni—Co—Si based copper alloy sheet material suitable for electrical or electronic parts such as connectors, lead frames, relays, and switches, which is particularly contemplated to decrease a factor of bending deflection, and to a method for producing the same.BACKGROUND ART[0002]Materials which are used for electrical or electronic parts as electric current carrying parts such as connectors, lead frames, relays, and switches are not only required to have good “electrical conductivity” for the purpose of suppressing the generation of Joule heat due to electric current conduction but required to have high “strength” for withstanding a stress given at the time of assembling or operation of an electrical or electronic appliance. In addition, electrical or electronic parts such as connectors are also required to have excellent bending workability because they are in general formed by bending work after stamping.[0003]In particula...

AI Technical Summary

Benefits of technology

[0027]According to the present invention, it is possible to realize a copper alloy sheet material with satisfactory bending workability, which has properties of an electrical conductivity of 30% IACS or more, a 0.2% yield strength of 950 MPa or more, and a factor of bending deflection is small, it is possible to increase the amount of bending deflection until the permanent deformation is started, but in view of the fact that the 0.2% yield strength is high, it is possible to improve an “inserting feeling” of a terminal portion in electric current conduction parts such as connectors and lead frames.

Problems solved by technology

However, there is involved such a drawback that the electrical conductivity is low as, for example, from about 10 to 15% IACS.

However, in this alloy system, it is not always easy to respond to higher strength.

However, when the addition amounts exceed a certain extent (for example, Ni: about 3%, Si: about 0.7%), the increase of the strength tends to be saturated, and it is extremely difficult to attain a 0.2% yield strength of 950 MPa or more.

In addition, the excessive addition of Ni and Si easily brings a lowering of the electrical conductivity or a lowering of bending workability due to coarsening of a Ni—Si based precipitate.

However, when the finish rolling ratio increases, the bending workability, in particular, bending workability in “bad way bending” with the rolling direction as a warped axis is conspicuously deteriorated.